Did you try to manually bring up the VM on the other host by any chance? Using the VMWare Console? If so, did you specify 'keep' or 'create' when you tried to bring up the 'copy' on the other host? If you selected 'create' then the virtual MAC addresses of the ethernet cards changed and that may be causing your issue. You must select 'keep' to keep the virtual machine ID (and all virtual NIC mac addresses) identical or Linux will think it's a new interface. Hence the eth1 designation now. (it still knows about eth0 having mac address X, so it adds eth1 with the new mac address).
I've had this issue a few times myself so what I do on the vmware server 'clusters' I build with this is I move one of the vm's by hand to the other server (by killing heartbeat) while I have the vmware console up and running. I shutdown the vm, kill heartbeat (to make everything move) then manually 'start' the VM on the 2nd box. That time I get the prompt about creating/keeping/always create/always keep. Pick always keep and you should be OK.
Any questions fire away... i'm actually in process of building a new pair of servers this week using DRBD 8.3 & VMWare Server 2.0. (need a bunch of changes from the howto to get it to work but not too bad so far).